My Gible is EV training for attack and it just beat 5 Weepinbell all at once. Gible is holding a Power Bracer and doesn't have Pokérus, just Power Bracer. Now if I beat a horde of Weepinbell, how much Ev will Gible gain? 2 EV x 5 = 10 + 4 from Power Bracer = 14 or 2 EV + 4 from Power Bracer = 6 x 5 =30? So how much EV will I gain? 14 or 30?

So what you mean is that all in all I get 30 EV's for defeating 5 Weepinbell? Does the Power item adds 4 EVs for every Pokémon defeated or does it add 4 EV's to the total number of EVs gained after battle?

The power bracer adds 4+ to the pokemons ev field = Weepinbell has 2attack ev's each. With power item it goes from 2 too 6 which would eventually give you the 60 without pokers or macho brace. Hope you find it useful

The game counts pokemon when training EVs you would get 30Atk EVs. If you are unsure about which EVs you can go to Super Training (bottom screen) and see what was added. And if it's hard to find hordes you could use a Pokemon with sweet scent. Works like honey and Bulba line learns it at lv 21/23/23.